Hypertension in Japan ranks first among reasons why patients attend hospitals. According to the National Life Fundamental Survey of Ministry of Health and Welfare (fiscal 1998), in Japan, 64 patients per 1000 were admitted to hospitals for hypertension.
Heart diseases such as angina pectoris, myocardial infarction and heart failure and cerebrovascular diseases such as cerebral infarction, cerebral hemorrhage and subarachnoid hemorrhage are closely related to hypertension and rank second and third, respectively, among the causes of death of the Japanese.
Hypertension may be treated by the administration of blood-pressure lowering pharmaceuticals such as diuretics, sympathetic inhibitors, vasodilators or angiotensin-converting enzyme inhibitors. Such drugs are mainly applied to patients suffering from severe hypertension. Although many of the pharmaceuticals administered to treat hypertension are satisfactory in their effectiveness, significant side-effects such as tachycardia and bradycardia can be a serious burden for patients.
Hypertension, especially its milder forms, may also be treated by generally improving lifestyle, such as through dietetic therapy, kinesitherapy and limitation of alcoholic intake or smoking. The importance of such changes in lifestyle is now being increasingly recognized and appreciated, not only for milder forms of hypertension, but also for more severe cases.
Above all, improvement of eating habits has received great attention. There exist a large number of foods, which have traditionally been said to have blood pressure lowering action. Food products have been briskly searched in order to identify and isolate components that lower blood pressure.
It has been reported that phenols such as caffeic acid contained crude form in the spike of Schizonepeta tenuifolia Briq. exerts calcium antagonism and may be useful for the treatment of vascular diseases such as hypertension (Japanese Patent Application Laid-Open (Kokai) No. Hei 4-243822).
The use of the juice of an unripe fruit such as apples, pears, peaches or similar fruits belonging to the family Rosaceae has also been proposed as a hypotensor. Such juice contains, as polyphenols, caffeic acid and chlorogenic acid having angiotensin I converting enzyme (ACE) inhibitory action (Japanese Patent Application Laid-Open (Kokai) No. Hei 8-259453.
However, foods which are said to be effective for lowering blood pressure or their effective ingredients are not always satisfactory in their effectiveness and many of them do not start to exert significant blood pressure reducing effects immediately after intake or exert long-last anti-hypertensive effects.
Therefore, one object of the present invention is to provide a preventive or remedy for hypertension which has excellent safety, does not become a burden for patients even by daily intake, has higher antihypertensive action and exerts significant prompt and/or long-lasting antihypertensive effects.